antimicrobial chemical agent.

Herz Antimicrobial chemical agents are those compounds that are obtained naturally or synthetically or semisynthetically and are able to inhibit gr owth and metabolism or even kill the microorganisms when used in the small amount. The examples of antimicrobial chemical agents are Disinfectant, Antiseptics, Antibiotics etc.

Ideal antimicrobial agent:

Antimicrobial agents having following characters are known as ideal antimicrobial agents;

• Antimicrobial activity: Ideal antibiotic chemical agent must posses antimicrobial activity i.e the ability to kill or inhibit microbial growth and metabolism, the agent should have the broad spectrum of antimicrobial activity when used in low concentration.
• Solubility: The agent must be soluble either in water or in the solvent used worldwide.
• Stability: The substance should be stable regarding it's antimicrobial activity for the period of time.
• Selective toxicity: Ideal antimicrobial agent must be toxic to microorganisms of the target but not to other organism and the host cell.
• Homogeneity: The pure chemicals must be homogenous in action. The preparation of the agent should also be homogenous ideal but not possible to achieve generally.
• Neutrality: The agent must not have to combine or react with organic compounds in the host body.
• Active at room temperature: The agent must have to show antimicrobial activity room temperature or at body temperature.
• Penetration ability: The agent must have penetration ability to diffuse to reach to target organs or site of action inside microbial or host body.
• Non-corrosive and now- staining; It should not be corrosive resting, staining and disturbing in nature.
• Non-Odourless: The agent should be either odourless or have the pleasant smell.
• Availability; The agent must be available in large quantities at a reasonable prise widely.

Groups of antimicrobial chemical agent:

There are various types of antimicrobial chemical agent. Some of them are described below;

• Phenol and phenolic compound:

Phenol and phenolic compounds like carboxylic acid , hexylresorcinol etc. ae commonly used antimicrobial agents.The carboxylic acid is the solution of phenol. It was first used in surgical incisions and wounds. Later on, the spray of phenol was used. Phenol is powerful disinfectants and phenol coefficient techniques is used for disinfection. A 5% aqueous solution of phenol kills vegetative cells of microorganisms. The addition of chemical substituents in the phenol ring structure enhances antimicrobial activity.The photos act over the microorganisms in following ways;

1. Disruption of the cell.
2. Precipitation of cell protein.
3. Inactivation of enzymes.
4. Leakage of amino acids from the cell.
5. The lethal effect due to physical damage so phenol kills microorganisms by one or more of the ways.

• Alcohols:

Alcohols are effective to kill the vegetative cells which used in 50-90% in concentration. Practically 70% of alcohol is used for disinfection. As higher concentration alcohol dehydrates cell so rapidly absolute alcohol cannot penetrate cells and does nor show antimicrobial activity. Alcohol cannot kill bacterial endospore. Ethanol is less active than ethanol and is more toxic and poisonous to organisms. So methanol is not used in the laboratory. A 70% ethanol is highly used, it has more activity than methanol ,propanols have more activity than ethanols than increased molecular weight. Alcohol of four or more carbon is not used due to it's immiscible nature.A 60% alcohol is effective to kill the virus but extraneous protein reacts and protects the virus from alcohols.

• Halogens:

They are group VIIa elements of the modern periodic table.It is one of the oldest and germicidal agent. Some useful halogens are;

1. Iodine:iodine is slightly soluble in water but soluble readily in aqueous alcohol and solution of KI and NaI. various proportions of Iodine and other solubilizing agents like iodine are used to kill microorganisms traditionally. a mixture of iodine with surface agents acts as carried or solubilizers of iodine which is so called endospores.
2. Chlorine and chlorine compounds:Chlorine is the form of gas or in the certain chemical which is widely used for disinfection . Chlorine gas is compressed to liquid form and is universally used for purification of municipal water supply. Handling chlorine gas is difficult so many chlorine compounds have been prepared for the practical uses.

• Heavy metals and their compounds:

mercury, silver, and copper are used singly or in compounds form to control microorganisms. heavy metals combine with cellular proteins and inactivate them. Mercuric chlorine inactivates sulfyhydralgroups of sulphur containing peptides. High concentration salt of heavy metals kills microorganisms by protein coagulation technique.they sometimes also kills microorganisms by precipitation technique.

• Aldehydes:

The organic compounds having CHO- functional group are called aldehydes. Aldehydes of low molecular weight like formaldehyde and dialdehyde are used in laboratory and industry to control both vegetative cells and spores of microorganism.An aqueous solution of formaldehyde contains 30-40% of formaldehyde and is used to sterilize some instruments disinfectants and enclosed areas.

• Dyes:

Triphenylmethane and acridine dyes are used in the microbial control.Triphenylmethane dyes are used to control gram-positive bacteria but 10 times more concentrated dyes are used to kill the gram-negative bacteria. Acridine dyes are selectively used to kill particular microorganism. It has low antifungal activity They are mostly used in wounds and burn infection as preservatives of operation patient.

• Synthetic Detergents:

Surface tension reductant or wetting agents used primarily for cleaning of surfaces are called synthetic detergents or surfactants that neither undergoes precipitation at alkaline or acidic p^H nor undergoes deposition of minerals in hard water. Some of them are bactericidal in nature. They are anionic,cationic and non-ionic types. Cationic detergents are more strong germicidal agents.

• Gases Agents:

Heat affecting equipment /materials like plastic syringes, blood transfusion apparatus, catheterization equipment etc are sterilized by gaseous agents such as ethylene oxide formaldehyde etc. ethylene oxide is liquid at 1.8^oc and vapourises above this temperature. It is the sporidal gas having high penetration ability. The concentration of gas used temperature and humidity affects the level of antimicrobial action. Alkylation of different protein and the enzyme having the functional group ,mechanism of inactivating cellular activities ultimately kills microorganisms.

References:

C.H.Collins. (1995). Microbiological Methods. Oxford Univ Press.

D.Greemwood, R. S. (2002). Medical Microbiology. London: Churchill Livingstone.

M.J.Pelezar. (1993). Microbiology. Tata McGraw hill.

M.T.Madigan, J. a. (1997). Biology of microorganisms. London: Prentice hall International Inc.

R.N.Atlas. (1984). Fundamentals and Applications. NewYork: MacMiHiam Publishing Co.